1. Field of the Invention
This invention is in the field of medicinal chemistry. In particular, the invention relates to substituted 2-aryl-4-arylaminopyrimidines and analogs, and the discovery that these compounds are activators of caspases and inducers of apoptosis. The invention also relates to the use of these compounds as therapeutically effective anti-cancer agents.
2. Related Art
Organisms eliminate unwanted cells by a process variously known as regulated cell death, programmed cell death or apoptosis. Such cell death occurs as a normal aspect of animal development as well as in tissue homeostasis and aging (Glucksmann, A., Biol. Rev. Cambridge Philos. Soc. 26:59-86 (1951); Glucksmann, A., Archives de Biologie 76:419-437 (1965); Ellis, et al., Dev. 112:591-603 (1991); Vaux, et al., Cell 76:777-779 (1994)). Apoptosis regulates cell number, facilitates morphogenesis, removes harmful or otherwise abnormal cells and eliminates cells that have already performed their function. Additionally, apoptosis occurs in response to various physiological stresses, such as hypoxia or ischemia (PCT published application WO96/20721).
There are a number of morphological changes shared by cells experiencing regulated cell death, including plasma and nuclear membrane blebbing, cell shrinkage (condensation of nucleoplasm and cytoplasm), organelle relocalization and compaction, chromatin condensation and production of apoptotic bodies (membrane enclosed particles containing intracellular material) (Orrenius, S., J. Internal Medicine 237:529-536 (1995)).
Apoptosis is achieved through an endogenous mechanism of cellular suicide (Wyllie, A. H., in Cell Death in Biology and Pathology, Bowen and Lockshin, eds., Chapman and Hall (1981), pp. 9-34). A cell activates its internally encoded suicide program as a result of either internal or external signals. The suicide program is executed through the activation of a carefully regulated genetic program (Wyllie, et al., Int. Rev. Cyt. 68:251 (1980); Ellis, et al., Ann. Rev. Cell Bio. 7:663 (1991)). Apoptotic cells and bodies are usually recognized and cleared by neighboring cells or macrophages before lysis. Because of this clearance mechanism, inflammation is not induced despite the clearance of great numbers of cells (Orrenius, S., J. Internal Medicine 237:529-536 (1995)).
It has been found that a group of proteases are a key element in apoptosis (see, e.g., Thornberry, Chemistry and Biology 5:R97-R103 (1998); Thornberry, British Med. Bull. 53:478-490 (1996)). Genetic studies in the nematode Caenorhabditis elegans revealed that apoptotic cell death involves at least 14 genes, two of which are the pro-apoptotic (death-promoting) ced (for cell death abnormal) genes, ced-3 and ced-4. CED-3 is homologous to interleukin 1 beta-converting enzyme, a cysteine protease, which is now called caspase-1. When these data were ultimately applied to mammals, and upon further extensive investigation, it was found that the mammalian apoptosis system appears to involve a cascade of caspases, or a system that behaves like a cascade of caspases. At present, the caspase family of cysteine proteases comprises 14 different members, and more may be discovered in the future. All known caspases are synthesized as zymogens that require cleavage at an aspartyl residue prior to forming the active enzyme. Thus, caspases are capable of activating other caspases, in the manner of an amplifying cascade.
Apoptosis and caspases are thought to be crucial in the development of cancer (Apoptosis and Cancer Chemotherapy, Hickman and Dive, eds., Humana Press (1999)). There is mounting evidence that cancer cells, while containing caspases, lack parts of the molecular machinery that activates the caspase cascade. This makes the cancer cells lose their capacity to undergo cellular suicide and the cells become cancerous. In the case of the apoptosis process, control points are known to exist that represent points for intervention leading to activation. These control points include the CED-9-BCL-like and CED-3-ICE-like gene family products, which are intrinsic proteins regulating the decision of a cell to survive or die and executing part of the cell death process itself, respectively (see, Schmitt, et al., Biochem. Cell. Biol. 75:301-314 (1997)). BCL-like proteins include BCL-xL and BAX-alpha, which appear to function upstream of caspase activation. BCL-xL appears to prevent activation of the apoptotic protease cascade, whereas BAX-alpha accelerates activation of the apoptotic protease cascade.
It has been shown that chemotherapeutic (anti-cancer) drugs can trigger cancer cells to undergo suicide by activating the dormant caspase cascade. This may be a crucial aspect of the mode of action of most, if not all, known anticancer drugs (Los, et al., Blood 90:3118-3129 (1997); Friesen, et al., Nat. Med. 2:574 (1996)). The mechanism of action of current antineoplastic drugs frequently involves an attack at specific phases of the cell cycle. In brief, the cell cycle refers to the stages through which cells normally progress during their lifetimes. Normally, cells exist in a resting phase termed Go. During multiplication, cells progress to a stage in which DNA synthesis occurs, termed S. Later, cell division, or mitosis occurs, in a phase called M. Antineoplastic drugs such as cytosine arabinoside, hydroxyurea, 6-mercaptopurine, and methotrexate are S phase specific, whereas antineoplastic drugs such as vincristine, vinblastine, and paclitaxel are M phase specific. Many slow growing tumors, for example colon cancers, exist primarily in the Go phase, whereas rapidly proliferating normal tissues, for example bone marrow, exist primarily in the S or M phase. Thus, a drug like 6-mercaptopurine can cause bone marrow toxicity while remaining ineffective for a slow growing tumor. Further aspects of the chemotherapy of neoplastic diseases are known to those skilled in the art (See, e.g., Hardman, et al., eds., Goodman and Gilman""s The Pharmacological Basis of Therapeutics, Ninth Edition, McGraw-Hill, New York (1996), pp. 1225-1287). Thus, it is clear that the possibility exists for the activation of the caspase cascade, although the exact mechanisms for doing so are not clear at this point. It is equally clear that insufficient activity of the caspase cascade and consequent apoptotic events are implicated in various types of cancer. The development of caspase cascade activators and inducers of apoptosis is a highly desirable goal in the development of therapeutically effective antineoplastic agents. Moreover, since autoimmune disease and certain degenerative diseases also involve the proliferation of abnormal cells, therapeutic treatment for these diseases could also involve the enhancement of the apoptotic process through the administration of appropriate caspase cascade activators and inducers of apoptosis.
Eur. Pat. Appl. EP 407899 discloses aminopyrimidine derivatives with activity as fungicide: 
wherein,
R1 is H, alkyl, alkoxyalkyl, alkylthioalkyl, cycloalkyl, alkenyl, alkynyl, cycloalkyalkyl, substituted aminoalkyl, phenyl, phenylalkyl, phenoxyalkyl, phenylmercaptoalkyl or phenoxyphenoxyalkyl, wherein the phenyl-portions are optionally substituted;
R2, R3, R4 independently are H, alkyl or optionally substituted phenyl;
R5 is H, alkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, alkoxy, alkylthio, alkoxyalkyl, R7R8Nxe2x80x94, alkylthioalkyl, R7R8-alkyl, halogen, alkenyl, alkynyl, phenyl, phenoxy, phenylalkyl, phenoxyalkyl, phenylmercaptoalkyl, phenylmercapto, phenylalkoxy or phenylalkylthio, wherein the phenyl-portions are optionally substituted;
R6 is H, alkyl, alkoxy, alkenyloxy, alkynyloxy, alkylthio, halogen or optionally substituted phenyl; or
R5 and R6 are taken together to form a polymethylene group;
R7 and R8 independently are H, alkyl, alkoxyalkyl, hydroxyalkyl, alkylthioalkyl, alkenyl, substituted aminoalkyl, alkynyl, cycloalkyl, cycloalkylalkyl, which in the cycloalkyl-portion is optionally substituted, formyl, phenyl or phenylalkyl, which in the phenyl-portion is optionally substituted; or
R7 and R8 are taken together with the nitrogen atom to which they are attached to form an optionally substituted 5- to 7-member, saturated or unsaturated, heterocycle with 1 or 3 heteroatoms, which are the same or different; and the acid addition salts which are functional as fungicides.
WO 0127089 patent application discloses pyrimidine derivatives for the treatment of diseases or medical conditions mediated by cytokines: 
wherein,
m is 0, 1, 2 or 3 are each R1 group, which may be the same or different, is selected from hydroxy, halogeno, trifluoromethyl, cyano, mercapto, nitro, amino, carboxy, carbamoyl, formyl, sulphamoyl, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkylthio, (1-6C)alkylsulphinyl, (1-6C)alkylsulphonyl, (1-6C)alkylamino, di[(1-6C)alkyl]amino, (1-6C)alkoxycarbonyl, N-(1-6C)alkycarbamoyl, N,N-di-[(1-6C)alkyl]carbamoyl, (2-6C)alkanoyl, (2-6C)alkanoyloxy, (2-6C)alkanoylamino, N-(1-6C)alkyl-(2-6C)alkanoylamino, N-(1-6C)alkylsulphamoyl, N,N-di-[(1-6C)alkyl]sulphamoyl, (1-6C)alkanesulphonylamino and N-(1-6C)alkyl-(1-6C)alkanesulphonylamino, or from a group of the formula:
Q1xe2x80x94X1xe2x80x94
wherein X1 is a direct bond or is selected from O, S, SO, SO2, N(R4), CO, CH(OR4), CON(R4), N(R4)CO, SO2N(R4), N(R4), N(R4)SO2, OC(R4)2, SC(R4)2 and N(R4)C(R4)2, wherein each R4 is hydrogen or (1-6C)alkyl, and Q2 is aryl-(1-6C)alkyl, heteroaryl-(1-6C)alkyl, heterocyclyl or heterocyclyl-(1-6C)alkyl, or (R1)m is (1-3C)alkylenedioxy, and wherein any aryl, heteroaryl or heterocyclyl group within a substituted on R1 optionally bears 1, 2 or 3 substituents,
R3 is hydrogen, halogeno or (1-6C)alkyl;
n is 0, 1 or 2 and each R1 group, which may be the same or different is selected from hydroxy, halogeno, trifluoromethyl, cyano, mercapto, nitro, amino, carboxy, (1-6C)alkoxycarbonyl, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkylamino and di[(1-6C)alkyl]amino;
p is 0, 1, 2, 3, or 4; and
Q1 is aryl or heteroaryl and Q1 is optionally substituted with 1, 2, or 3 substituents, which may be the same of different, selected from hydroxy, halogeno, trifluoromethyl, cyano, mercapto, nitro, amino, carboxy, carbamoyl, formyl, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkylthio, (1-6C) alkylsulphinyl, (1-6C)alkylsulphonyl, (1-6C)alkylamino, di[(1-6C)alkyl]amino, (1-6C)alkoxycarbonyl, N-(1-6C)alkycarbamoyl, N,N-di-[(1-6C)alkyl]carbamoyl, (2-6C)alkanoyl, (2-6C)alkanoyloxy, (2-6C)alkanoylamino, N-(2-6C)alkyl-(2-6C)alkanoylamino, N-(2-6C)alkylsulphamoyl, N,N-di-[(1-6C)alkyl]sulphamoyl, (1-6C)alkanesulphonylamino and N-(1-6C)alkyl-(1-6C)alkanesulphonylamino, or with a (1-3C)alkylenedioxy group, or from a group of the formula:
xe2x80x94X3xe2x80x94Q4
wherein X3 is a direct a bond or is selected from 0 and N(R8), wherein R8is hydrogen or (1-6C)alkyl, and Q4 is aryl, aryl-(1-6C)alkyl, heteroaryl, heteroaryl-(1-6C)-alkyl, heterocyclyl or heterocyclyl(1-6C)alkyl, and any Q4 group optionally bears 1 or 2 substituents, which may be the same of different, selected from halogeno, trifluoromethyl, cyano, hydroxy, amino, (1-6C)alkyl, (1-6C)alkoxy, (1-6C)alkylamino and di-[(1-6C)alkyl]amino.
WO 0027824 patent application discloses substituted pyrimidine compositions and methods of use. The compounds are said to have activity as inhibitors of phospholipase A2, and are useful in treating disorders mediated by phospholipase A2: 
wherein,
the symbol R1 represents a C1-C6 alkyl, C1-C6 alkoxy or halogen atom. The symbol R2 represents a phenyl group, substituted phenyl group, benzyl moiety, substituted benzyl moiety, C3-C7 cycloalkyl, or substituted C3-C7 cycloalkyl. The symbol R3 represents a hydrogen or C1-C6 alkyl group. The symbol R4 represents xe2x80x94H, xe2x80x94OH, xe2x80x94N3 or xe2x80x94NHCOCH3. The symbol R5 represents H or alkyl, preferably H.
U.S. Pat. No. 6,156,755 discloses the use of pyridine derivatives for the prevention of cancer: 
wherein,
R1 is hydrogen, halogen, cyano, nitro, trifluoromethyl, amino, (C1-C6)-alkyl, (C1-C6)-hydroxyalkyl, (C1-C6)-alkoxy, (C6-C12)-aryl, (C1-C6)-alkoxycarbonyl-(C1-C6)-alkyl, (C1-C6)-alkyl-S-(C1-C6)-alkyl, (C1-C6)-alkyl-SO-(C1-C6)-alkyl, (C1-C6)-alkyl-SO2-(C1-C6)-alkyl, dihydroxy-(C1-C6)-alkyl, aryl, heteroaryl, heteroaryl-(C1-C6)-alkyl, aryl-(C1-C6)-alkyl, (C1-C6)-alkoxycarbonylaryl, aryl-(C1-C6)-alkyloxy or heteroaryl-(C1-C6)-alkyloxy, heteroaryl is pyridyl, furyl, tetrahydrofuryl, thienyl, imidazolyl, pyrazolyl, triazolyl, thiazolyl, oxazolyl, benzothiazolyl;
R2, R3 independently of one another are hydrogen, (C1-C6)-alkyl, (C6-C12)-aryl, (C6-C12)-arylalkyl having 1-4 alkyl carbon atoms, where aryl can be substituted by one to three substituents selected from the group consisting of chlorine, bromine, trifluoromethyl, (C1-C6)-alkyl, (C1-C6)-alkoxy, or R2, R3, together with the nitrogen to which they are bonded, form the azetidino, pyrrolidino, piperidino, piperazino or morpholino group, where the heterocycles can be substituted by one or two substituents selected from the group consisting of chlorine, bromine, trifluoromethyl, (C1-C6)-alkyl, (C1-C6)-alkoxy, xe2x80x94S-(C1-C6)-alkyl, xe2x80x94SO-(C1-C6)-alkyl, xe2x80x94SO2-(C1-C6)-alkyl, sulfamoyl, N-(C1-C4)-alkylsulfamoyl, N,N-(C1-C4)-dialkylsulfamoyl, (C1-C6)-alkoxycarbonyl, N,N-(C1-C4)-dialkylcarbamoyl, N-(C1-C4)-alkylcarbamoyl, N-(C6-C12)-arylcarbamoyl, (C6-C12)-arylcarbamoyl substituted in the aryl radical by (C1-C4)-alkyl, (C1-C4)-alkoxyl, halogen, NO2, NH2, CN or CF3, (C6-C12)-arylcarbonyl substituted in the aryl radical by (C1-C4)-alkoxy, halogen, NO2, NH2, CN or CF3, (C1-C6)-alkylsulfonyl, (C1-C6)-alkylsulfinyl, (C6-C12)-arylsulfonyl, (C6-C12)-arylsulfonyl substituted in the aryl radical by (C1-C4)-alkyl, (C1-C4)-alkoxy, halogen, NO2, NH2, CN or CF3, heteroarylcarbonyl or heteroarylsulfonyl;
R4 and R5 independently of one another are hydrogen, halogen, cyano, nitro, trifluoromethyl, amino, (C1-C6)-alkyl, (C1-C6)-hydroxyalkyl, (C1-C6)-alkoxy, (C6-C12)-aryl, naphthyl, furyl, where (C6-C12)-aryl, naphthyl and furyl can be substituted by one or two substituents selected from the group consisting of chlorine, bromine, trifluoromethyl, (C1-C6)-alkyl, (C1-C6)-alkoxy, xe2x80x94S-(C1-C6)-alkyl, xe2x80x94SO-(C1-C6)-alkyl, xe2x80x94SO2-(C1-C6)-alkyl, hydroxyl; and their physiologically tolerable salts.
The present invention is related to the discovery that substituted 2-aryl-4-arylaminopyrimidines and analogs, as represented in Formula I, are activators of the caspase cascade and inducers of apoptosis. Thus, an aspect of the present invention is directed to the use of compounds of Formula I as inducers of apoptosis.
Compounds of the present invention are represented by Formula I: 
or pharmaceutically acceptable salts or prodrugs thereof, wherein:
Ar1 and Ar2 are independently and optionally substituted aryl or heteroaryl;
A is N or Cxe2x80x94R2;
R1 and R2 are independently hydrogen, halo, haloalkyl, aryl, fused aryl, carbocyclic, a heterocyclic group, a heteroaryl group, alkyl, alkenyl, alkynyl, arylalkyl, arylalkenyl, arylalkynyl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl, carbocycloalkyl, heterocycloalkyl, hydroxyalkyl, nitro, amino, cyano, acylamido, hydroxy, thiol, acyloxy, azido, alkoxy, aryloxy, arylalkoxy, haloalkoxy, carboxy, carbonylamido or alkylthiol; and
R3 is hydrogen, an optionally substituted alkyl or cycloalkyl.
A second aspect of the present invention is to provide a method for treating, preventing or ameliorating neoplasia and cancer by administering a compound of Formula I to a mammal in need of such treatment.
Many of the compounds within the scope of the present invention are novel compounds. Therefore, a third aspect of the present invention is to provide novel compounds of Formula I, and to also provide for the use of these novel compounds for treating, preventing or ameliorating neoplasia and cancer.
A fourth aspect of the present invention is to provide a pharmaceutical composition useful for treating disorders responsive to the induction of apoptosis, containing an effective amount of a compound of Formula I in admixture with one or more pharmaceutically acceptable carriers or diluents.
A fifth aspect of the present invention is directed to methods for the preparation of novel compounds of Formula I.